Last week's death on the set of "Midnight Rider," the Gregg Allman biopic directed by Randall Miller and starring William Hurt, has prompted an outpouring of support from the Hollywood community. A Facebook page called Slates for Sarah was established to honor Sarah Jones, the second camera assistant who was struck by a train while the movie was filming on a railroad bridge. Various entertainment-industry insiders are posting photos of clapperboards from their respective film and TV sets that contain...